The present invention relates to a Apparatus for medical treatment, in particular of tissue by means of laser light
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Applicators for medical treatment of living tissue with the help of lasers are known. In particular, the surgical removal or reduction in volume of prostate tissue by means of laser light is known. Holmium lasers are used as the light source, which generate strong light output at an emission wavelength (light wavelength) in the micrometer range (approx. 2123 nm), which makes very good tissue ablation possible. For this purpose, the laser light is coupled into one end of a multimode optical conducting fiber that where possible comprises a large numerical aperture (NA), and re-emerges from the forward surface of the other end. The optical conducting fiber usually terminates in a distal end piece at the straight (longitudinally aligned) light emission end, so that the laser light is emitted from its forward surface.
Because of its optical wavelength, the light from the holmium laser is absorbed strongly by water, whereby the water-bearing prostate tissue is evaporated when irradiated. The minor penetration depth into the tissue of less than one millimeter results in very thin incisions when the prostate tissue is contacted directly by the optical fiber or by the associated distal end piece, therefore immediately ablating the tissue. Visual verification may be performed with an endoscope.
In order to conduct light, the optical conducting fiber comprises a central core, which is primarily composed of quartz glass. At least one cladding (glass sheath) is arranged over the core, as well as a plastic sheath over this for protection.
A disadvantage in the treatment is that the laser light is not emitted laterally from the optical conducting fiber, but rather from the forward surface in the direction of the fiber's longitudinal axis.
It would therefore be desirable and advantageous to provide an apparatus (applicator) for medical treatment, in particular for the removal and reduction of living tissue, by means of an optical conducting fiber that is then in contact (contact mode) with the tissue, and in which the laser light is emitted with virtually no loss in a direction transverse to the principally straight longitudinal extent of the optical conducting fiber. The living tissue is especially prostate tissue.